Well, from the sounds of it you have a girl with a urinary tract infection. If she is not spayed then it is possible that she has a uterine infection. Being a schnauzer she can be prone to infection and the development of urinary crystals. This is actually a common problem with schnauzers as well as the formation of bladder stones. I do suggest a trip to the vet in the near future for a urinalysis to rule out an infection, crystals and stones.
Other possible causes are leaking urine as a result of urinary incontinence.
Please let me know if further assistance is needed.